How Treasure Maps Work in ESO

First, you need to actually have one. The ones I've seen are blue, and they typically are named by their region, along with a roman number. Second, you have to have it in the inventory in order for you to be able to actually dig up and loot the treasure. Once you dig up the treasure, the map in your inventory gets used up.

Yes, that's right. Treasure maps are one time use per map.

The map itself shows you where it is with an X on the map.  However, simply googling the treasure map will give you a much better idea where you need to be to find the treasure.  I'm sure it will be an add-on someday so that you know exactly where to go in-game but for now, there's youtube and various websites that will guide you right to it.

You will see a mound of dirt if you get to the right spot.  Again, if you don't have the map in inventory, you will not see the mound, nor will you be able to dig anything up.

For example:

Bleakrock II Treasure location

Happy Treasure hunting!